The Korean won is tumbling amid 'geopolitical anxiety'

The won closed down by 0.5% at 1,143.64 per dollar. It has fallen for five consecutive session, and for nine out of the past 10.

"Geopolitical anxiety is still running high, and the South Korean won and the Kospi bore the brunt," Marc Chandler, global head of currency strategy at Brown Brothers Harriman, said.

Earlier on Monday, China and South Korea agreed to impose tougher sanctions on North Korea if it carries out nuclear and long-range missile tests, according to Reuters.

Meanwhile, a US Navy strike group is heading to the region amid concerns that Pyongyang may be prepping for another nuclear test.

As for the rest of the world, here's the scoreboard as of 8:02 a.m. ET:

The US dollar index is little changed at 101.20. Later on Monday, Fed Chair Janet Yellen is giving a speech at the University of Michigan.

The euro is little changed at 1.0577 against the dollar. Over in France, the latest Kantar Sofres poll, published late Sunday, shows far-left candidate Jean-Luc Melenchon at 18% support for the first round, just 1 point behind Republican Francois Fillon, Bloomberg says. Independent candidate Emmanuel Macron and far-right candidate Marine Le Pen are tied at 24%.

The Russian ruble is little changed at 57.2038 per dollar, while Brent crude oil, the international benchmark, is up by 1.2% at $55.90 per barrel.